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H. J. COGSWELL; WATGHMAKBRS LENGTH GAGE. No. 531,435-, Patented Deo. 25, 18.94.

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@Moc-w 1 traverse the graduated arm and by its posi- UNITED STATES PATENT Orricn.

HENRY J. COGSWELL, OF HARTFORD, CONNECTICUT.

WATCHMAKERS LNGTH-GAGE.

SPECIFICATION forming part of Letters Patent No. 531,435, dated December 25, 1894.

v Application filed october 1,1894. seriainaszmvs. (Numdam To all whom may concern.-

Beit known that I, HENRY J. CoGswELL,a

citizen of the United States, and a resident of i Hartford,'in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Watchmakers Length-Gages, of which the following is a full, clear, and exact description, whereby any one skilled in the art can make and use the same. The object of my invention is to provide a tool that shall be particularly adapted for use by repairers for the measurement of the length of the sta or pinion or of like small shafts where great accuracy is required, and to this end my invention consists in the details of the several parts making upthe gage as a whole and in the combination of the parts as. more particularly hereinafter described and pointed out in the claims.

Referring to the drawings: Figure l i's a View of the implement. Fig. 2 is a detail view' -of the implement illustrating its manner of' use. Fig. 3 is a detail view on enlarged scale in section through parts ofthe gage showing the position of such parts when the implementV is not in use.

Fig. 4 is a detail view in section on enlarged scale showing the position of parts when used inmeasuring.

In the accompanying drawings the letter ct denotes the handle ofthe tool having a hollow portion'or shank b within which part of the mechanism is supported. From a point about midway of the handle and shank a graduated arm c extends for about ninety degrees, the end of an index arm d being arranged to tion indicate the distance traveled from the zero point on the scale.

The index arm d is pivoted to a bracket ke formed on or secured to the tool near the end of the shank, the index arm having a branch f which extends through a slot in the shank and encounters the top 'of a plunger g.

The plunger g is located within the hollow part of the shank the broadened headg forming a shoulder which rests against the shoulder b within the shank. The lower end of the i shank is provided with a nipple b2 and the end of this nipple and of theplunger g are in precise alignment when the plunger is at the ioweriimirof its playas Shown in Fig 3 of the drawings.

A piston h looselyarranged within the tubular shankV is forced downward by a spiralv springt'and exertsacontinuous pressure upon the outer edgey of the branch f and tends to hold the index arm d in the position with re lation to the handle, as shown in Fig. l of the drawings, the index finger being on zero of the scale.

The plunger and several other parts of the mechanism are in the relative position shown in Figs. land 3 when the' plunger is at the lower limitv of its play, but as soon as a shaft, a wire or like article is thrust into the nipple and forces the plunger back the index arm /will travel along the scale a distance proportioned to the extent of movement of the plun'- ger. This proportion of movement of the index finger depends upon the ratio between the distance from the pivot e to the end of the branch as compared with the distance from vlied so as to become `an easily noted quantity on the scale marked on the arm. In the scale `as shown in the drawings the movement of the plunger canvbe read to the nearest thousandth of an inch. -e

The outer end ofthe index arm is forked the extreme of one fork forming the finger and the other forming a guide which travels along on the back of the arm on which the scale is marked. l

The contact parts that is, the end of the branch f and the surfaces of the plunger and piston, as well as the end of the nipple and outer end of the plunger, are of hardened steel and thus adapted to endure continued use for a long period of time without any appreciable wear of the surfacessuch as would affect the accuracy of the implementas a measuring tool. By the useofthis tool the 95 V4lengths of shafts and other small parts where Contact with the shank or bracket limits and determines the outward swinging movement of the arm d.

I claim as my invention- 1. In combination in alength gage a handle, the tubular shank terminating in a nipple, an index arm pivoted to the shank with a branch extending Within the latter and in contact with a plunger, a plunger located within the shank and having a shoulder cooperating with the shoulder within the shank whereby the outel` end of the plunger is held in exact alignment with the outer end ofthe nipple, a spring actuated piston arranged Within the plunger and pressing upon the branch, and a grad uated arm adapted to be traversed by the end of the index arm, all substantially as described.

stop on the lower end of the index arm limit- 3o ing the swinging play of the arm, all substantially as described.

HENRY J. COGSWELL. Witnesses:

ARTHUR B. JENKINS, J. A. CANTIN. 

